Storm Watch: "Dry lightning" possible early next week
The storms aren't likely to be as severe as the ones that triggered wildfires last year, forecasters said.
(Graphic by Solano NewsNet)
Weather forecasters are warning of the potential for thunderstorms with so-called “dry lightning” that could cross through portions of Northern California early next week.
On Thursday, meteorologists with the National Weather Service’s forecast office in San Francisco said monsoonal moisture is expected to reach the region between Sunday and Tuesday of next week.
“Some years, the monsoonal moisture fails to make it this far west, or lacks the instability to generate high based convection,” a weather forecaster wrote in a bulletin on Thursday. “Other years — say around 1 out every 2 to 3 — the ingredients come together for elevated convection, high based thunderstorms (and) dry lightning to occur.”
That scenario happened twice last year, including in mid-August, when lightning sparked several fires that ultimately merged into the massive LNU Lightning Complex wildfire.
Less than two days after it sparked, a portion of the wildfire crossed over from Napa County into Solano County. Hundreds of structures were destroyed by the blaze in rural parts of Vacaville, Fairfield and Winters.
Forecasters say last year’s monsoonal moisture system was strengthened by tropical moisture that remained from Tropical Storm Fausto and Hurricane Genevieve, which caused the stronger lightning storms that sparked the wildfires.
This year, the monsoonal moisture system is expected to be weaker because tropical moisture is expected to be “tightly bound to Hurricane Felicia,” a weather forecaster said. That hurricane is spinning well to the southwest of Baja California.
For this reason, meteorologists think this year’s dry lightning phenomenon will be less severe than the storms last year.
“That said, dry lightning — if it occurs — could still lead to new fire ignitions simply due to impacts from the drought,” a forecaster said, noting that vegetation inland were exceptionally dry due to a lack of normal precipitation.
“We will continue to monitor this situation closely as model data continues to stream in and post updates as they become available,” the forecast office said.
The monsoonal moisture is expected to bring one side benefit: A break from the exceedingly hot weather.
“This current scenario will be preceded by weeks of coastal drizzle and near to below normal temperatures for most of the region,” the forecaster wrote.
Areas that will see the biggest impacts of lower temperatures will be along Northern California’s waterways, including Vallejo and Benicia.
Further inland, temperatures “should remain well within what you would expect for July,” a meteorologist with the National Weather Service in Sacramento wrote in a separate weather bulletin, adding that the Delta breeze should help keep the heat to a minimum.